Carbon stock and its compartments in a subtropical oxisol under long-term tillage and crop rotation systems

Soil organic matter (SOM) plays a crucial role in soil quality and can act as an atmospheric C-CO2 sink under conservationist management systems. This study aimed to evaluate the long-term effects (19 years) of tillage (CT-conventional tillage and NT-no tillage) and crop rotations (R0-monoculture system, R1-winter crop rotation, and R2- intensive crop rotation) on total, particulate and mineral-associated organic carbon (C) stocks of an originally degraded Red Oxisol in Cruz Alta, RS, Southern Brazil. The climate is humid subtropical Cfa 2a (Köppen classification), the mean annual precipitation 1,774 mm and mean annual temperature 19.2 ºC. The plots were divided into four segments, of which each was sampled in the layers 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m. Sampling was performed manually by opening small trenches. The SOM pools were determined by physical fractionation. Soil C stocks had a linear relationship with annual crop C inputs, regardless of the tillage systems. Thus, soil disturbance had a minor effect on SOM turnover. In the 0-0.30 m layer, soil C sequestration ranged from 0 to 0.51 Mg ha-1 yr-1, using the CT R0 treatment as base-line; crop rotation systems had more influence on soil stock C than tillage systems. The mean C sequestration rate of the cropping systems was 0.13 Mg ha-1 yr-1 higher in NT than CT. This result was associated to the higher C input by crops due to the improvement in soil quality under long-term no-tillage. The particulate C fraction was a sensitive indicator of soil management quality, while mineral-associated organic C was the main pool of atmospheric C fixed in this clayey Oxisol. The C retention in this stable SOM fraction accounts for 81 and 89 % of total C sequestration in the treatments NT R1 and NT R2, respectively, in relation to the same cropping systems under CT. The highest C management index was observed in NT R2, confirming the capacity of this soil management practice to improve the soil C stock qualitatively in relation to CT R0. The results highlighted the diversification of crop rotation with cover crops as a crucial strategy for atmospheric C-CO2 sequestration and SOM quality improvement in highly weathered subtropical Oxisols.

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Long-term C-CO2 emissions and carbon crop residue mineralization in an oxisol under different tillage and crop rotation systems

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832011000300017 ◽

2011 ◽

Vol 35 (3) ◽

pp. 819-832 ◽

Cited By ~ 10

Author(s):

Ben-Hur Costa de Campos ◽

Telmo Jorge Carneiro Amado ◽

Carlos Gustavo Tornquist ◽

Rodrigo da Silveira Nicoloso ◽

Jackson Ernani Fiorin

Keyword(s):

Co2 Emissions ◽

Crop Rotation ◽

Crop Residue ◽

Crop Residues ◽

Cropping Systems ◽

Co2 Efflux ◽

C Mineralization ◽

Tillage Systems ◽

Soil C

Soil C-CO2 emissions are sensitive indicators of management system impacts on soil organic matter (SOM). The main soil C-CO2 sources at the soil-plant interface are the decomposition of crop residues, SOM turnover, and respiration of roots and soil biota. The objectives of this study were to evaluate the impacts of tillage and cropping systems on long-term soil C-CO2 emissions and their relationship with carbon (C) mineralization of crop residues. A long-term experiment was conducted in a Red Oxisol in Cruz Alta, RS, Brazil, with subtropical climate Cfa (Köppen classification), mean annual precipitation of 1,774 mm and mean annual temperature of 19.2 ºC. Treatments consisted of two tillage systems: (a) conventional tillage (CT) and (b) no tillage (NT) in combination with three cropping systems: (a) R0- monoculture system (soybean/wheat), (b) R1- winter crop rotation (soybean/wheat/soybean/black oat), and (c) R2- intensive crop rotation (soybean/ black oat/soybean/black oat + common vetch/maize/oilseed radish/wheat). The soil C-CO2 efflux was measured every 14 days for two years (48 measurements), by trapping the CO2 in an alkaline solution. The soil gravimetric moisture in the 0-0.05 m layer was determined concomitantly with the C-CO2 efflux measurements. The crop residue C mineralization was evaluated with the mesh-bag method, with sampling 14, 28, 56, 84, 112, and 140 days after the beginning of the evaluation period for C measurements. Four C conservation indexes were used to assess the relation between C-CO2 efflux and soil C stock and its compartments. The crop residue C mineralization fit an exponential model in time. For black oat, wheat and maize residues, C mineralization was higher in CT than NT, while for soybean it was similar. Soil moisture was higher in NT than CT, mainly in the second year of evaluation. There was no difference in tillage systems for annual average C-CO2 emissions, but in some individual evaluations, differences between tillage systems were noticed for C-CO2 evolution. Soil C-CO2 effluxes followed a bi-modal pattern, with peaks in October/November and February/March. The highest emission was recorded in the summer and the lowest in the winter. The C-CO2 effluxes were weakly correlated to air temperature and not correlated to soil moisture. Based on the soil C conservation indexes investigated, NT associated to intensive crop rotation was more C conserving than CT with monoculture.

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Long-term nutrient fertilization and the carbon balance of permanent grassland: any evidence for sustainable intensification?

10.5194/bg-2016-224 ◽

2016 ◽

Author(s):

Dario A. Fornara ◽

Elizabeth - Anne Wasson ◽

Peter Christie ◽

Catherine J. Watson

Keyword(s):

C Sequestration ◽

Pig Slurry ◽

Liquid Manure ◽

Cattle Slurry ◽

Soil C ◽

Permanent Grassland ◽

C Balance ◽

C Stocks ◽

Nutrient Fertilization

Abstract. Sustainable grassland intensification aims to increase plant yields while maintaining soils’ ability to act as sinks rather than sources of atmospheric CO2. High biomass yields, however, from managed grasslands can be only maintained through long-term nutrient fertilization, which can significantly affect soil carbon (C) storage and cycling. Key questions remain about (1) how long-term inorganic vs. organic fertilization influences soil C stocks, and (2) how soil C gains (or losses) contribute to the long-term C balance of managed grasslands. Using 43 years of data from a permanent grassland experiment we show that soils not only act as significant C sinks but have not yet reached C saturation. Even unfertilized-control soils showed C sequestration rates of 0.35 Mg C ha−1 yr−1 (i.e. 35 g C m−2 yr−1; 0–15 cm depth) between 1970 and 2013. High application rates of liquid manure (i.e. cattle slurry) further increased soil C sequestration to 0.86 Mg C ha−1 yr−1 (i.e. 86 g C m−2 yr−1) and a key cause of this C accrual was greater C inputs from cattle slurry. However, average coefficients of ‘Slurry-C retention’ suggest that 85 % of C added yearly through liquid manure is lost possibly via CO2 fluxes and organic C leaching from soils. Inorganically fertilized soils (i.e. NPK) had the lowest ‘C-gain-efficiency’ (i.e. unit of C gained per unit of N added) and lowest C sequestration (similar to control soils). Soils receiving cattle slurry showed higher C-gain and N-retention efficiencies compared to soils receiving NPK or pig slurry. We estimate that net rates of CO2-sequestration in the soil top 15 cm can offset 9-to-25 % of GHG emissions from intensive management. However, because of multiple GHG sources associated with livestock farming, the net C balance of these grasslands remains positive (9-to-12 Mg CO2-equivalent ha−1 yr−1), thus contributing to climate change. Further C-gain efficiencies (e.g. reduced enteric fermentation and use of feed concentrates, better nutrient-management) are required to make grassland intensification more sustainable.

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Distribution of organic carbon in the stable soil humic fractions as affected by tillage management

Canadian Journal of Soil Science ◽

10.4141/s06-059 ◽

2008 ◽

Vol 88 (1) ◽

pp. 99-106 ◽

Cited By ~ 10

Author(s):

Evah W Murage ◽

Paul Voroney

Keyword(s):

C Sequestration ◽

No Tillage ◽

Sampling Depth ◽

Soil C ◽

Tillage Practices ◽

Conventional Ct ◽

Humin Fraction ◽

Humic Fractions ◽

Soil C Sequestration

Soil humus comprises a large and stable pool of soil organic matter (SOM); hence a better understanding of the fate of C in soil humic fractions can provide valuable information for the development of alternative tillage practices that will lead to long-term soil C sequestration. We used δ13C techniques to investigate the effects of tillage on the dynamics of native (C3–C) and corn derived C (C4–C) in fulvic acid (FA), humic acid (HA) and humin fractions. Humic substances were extracted from soils cropped to corn for 11 yr and managed under either conventional (CT) or no-tillage (NT), and from a conventionally tilled soil under > 55 yr of tobacco/rye rotation. No-tillage resulted in higher proportions of C4–C in the upper 5 cm and generally lower C4–C proportions below 5 cm than CT. Up to 31, 27 and 34% of C4–C were assimilated into FA, HA and humin fractions, respectively, indicating that even the humin fraction, often described as passive, old or resistant, acted as a sink of recently added C, and that it is heterogeneous with some of its components being young. Recovery of large proportions of C3–C in the humic fractions demonstrated their importance in the long-term stabilization of SOM. Within each sampling depth, there were no unique differences in the distribution of C3–C among the three humic fractions, suggesting similar turnover of C3–C in all the fractions. Therefore, there was no unique active fraction corresponding with the concept of C pools with defined turnover characteristics used in models of SOM turnover. Key words: Soil humic fractions, corn derived C, native C, δ13C techniques, tillage practices

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Restoring organic matter in a cultivated, semiarid soil using crested wheatgrass

Canadian Journal of Soil Science ◽

10.4141/s00-001 ◽

2000 ◽

Vol 80 (3) ◽

pp. 429-435 ◽

Cited By ~ 9

Author(s):

D. Curtin ◽

F. Selles ◽

H. Wang ◽

R. P. Zentner ◽

C. A. Campbell

Keyword(s):

Organic Matter ◽

Carbon Dioxide Emissions ◽

C Sequestration ◽

Mitigation Strategies ◽

Organic C ◽

Crested Wheatgrass ◽

Soil C ◽

Sequestration Potential ◽

C Stocks

Planting of cultivated land with perennial forages may increase C sequestration in soil organic matter and contribute to atmospheric CO2 mitigation strategies. However, little is known of the effectiveness of introduced grasses in restoring organic C in cultivated soils of the Canadian prairies. Our objective was to evaluate the C sequestration potential of crested wheatgrass (CWG) (Agropyron cristatum L. Gaertn.), a widely introduced, early-season grass. In 1995 and 1996, we measured soil CO2 fluxes, C inputs in plant material and total soil C under CWG and a fallow-wheat (Triticum aestivum L.)-wheat rotation (F-W-W). These were two of the treatments in a replicated crop rotation experiment initiated in 1987 in southwestern Saskatchewan on a medium-textured soil that had previously been under long-term wheat production. Average to above-average growing season (1 May to 31 July) precipitation in 1995–1996 resulted in annual inputs of C in wheat residues of 3000–4500 kg ha−1. Growth of CWG, which was hayed and removed, was relatively poor in both years, but especially in 1995 when dry matter yield was only 1300 kg ha−1. For the 1988–1996 period, there was a strong correlation (R2 = 0.81; P < 0.001) between CWG yield and precipitation received in May, showing the importance of early spring rains determining CWG yield and C inputs to the soil. Carbon inputs under CWG (1200 kg ha−1 in 1995 and 2400 kg ha−1 in 1996) were less than under wheat but CO2-C emissions were similar under CWG and wheat. Soil C measurements in fall 1996 confirmed that CWG did not gain C relative to the F-W-W rotation. Although failure of CWG soil to store more C than cultivated soil may be partly because weather conditions during the experiment were more favourable for wheat than CWG, our results cast doubt on the ability of CWG to restore C stocks in prairie soils degraded by long-term cropping. Key words: Carbon sequestation, carbon dioxide emissions, wheat, crested wheatgrass, fallow

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Long-term nutrient fertilization and the carbon balance of permanent grassland: any evidence for sustainable intensification?

Biogeosciences ◽

10.5194/bg-13-4975-2016 ◽

2016 ◽

Vol 13 (17) ◽

pp. 4975-4984 ◽

Cited By ~ 19

Author(s):

Dario A. Fornara ◽

Elizabeth-Anne Wasson ◽

Peter Christie ◽

Catherine J. Watson

Keyword(s):

C Sequestration ◽

Pig Slurry ◽

Liquid Manure ◽

Cattle Slurry ◽

Soil C ◽

Permanent Grassland ◽

C Balance ◽

C Stocks ◽

Nutrient Fertilization

Abstract. Sustainable grassland intensification aims to increase plant yields while maintaining the ability of soil to act as a sink rather than sources of atmospheric CO2. High biomass yields from managed grasslands, however, can be only maintained through long-term nutrient fertilization, which can significantly affect soil carbon (C) storage and cycling. Key questions remain about (1) how long-term inorganic vs. organic fertilization influences soil C stocks, and (2) how soil C gains (or losses) contribute to the long-term C balance of managed grasslands. Using 43 years of data from a permanent grassland experiment, we show that soils not only act as significant C sinks but have not yet reached C saturation. Even unfertilized control soils showed C sequestration rates of 0.35 Mg C ha−1 yr−1 (i.e. 35 g C m−2 yr−1; 0–15 cm depth) between 1970 and 2013. High application rates of liquid manure (i.e. cattle slurry) further increased soil C sequestration to 0.86 Mg C ha−1 yr−1 (i.e. 86 g C m−2 yr−1) and a key cause of this C accrual was greater C inputs from cattle slurry. However, average coefficients of slurry-C retention in soils suggest that 85 % of C added yearly through liquid manure is lost possibly via CO2 fluxes and organic C leaching. Inorganically fertilized soils (i.e. NPK) had the lowest C-gain efficiency (i.e. unit of C gained per unit of N added) and lowest C sequestration (similar to control soils). Soils receiving cattle slurry showed higher C-gain and N-retention efficiencies compared to soils receiving NPK or pig slurry. We estimate that net rates of CO2-sequestration in the top 15 cm of the soil can offset 9–25 % of GHG (greenhouse gas) emissions from intensive management. However, because of multiple GHG sources associated with livestock farming, the net C balance of these grasslands remains positive (9–12 Mg CO2-equivalent ha−1 yr−1), thus contributing to climate change. Further C-gain efficiencies (e.g. reduced enteric fermentation and use of feed concentrates, better nutrient management) are required to make grassland intensification more sustainable.

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The crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa

Agronomy for Sustainable Development ◽

10.1007/s13593-021-00687-y ◽

2021 ◽

Vol 41 (2) ◽

Author(s):

Blessing Mhlanga ◽

Laura Ercoli ◽

Elisa Pellegrino ◽

Andrea Onofri ◽

Christian Thierfelder

Keyword(s):

Crop Rotation ◽

Southern Africa ◽

Cropping Systems ◽

Conservation Agriculture ◽

Conventional Tillage ◽

Yield Stability ◽

No Tillage ◽

The Stability ◽

Stability And Resilience

AbstractConservation agriculture has been promoted to sustainably intensify food production in smallholder farming systems in southern Africa. However, farmers have rarely fully implemented all its components, resulting in different combinations of no-tillage, crop rotation, and permanent soil cover being practiced, thus resulting in variable yield responses depending on climatic and soil conditions. Therefore, it is crucial to assess the effect of conservation agriculture components on yield stability. We hypothesized that the use of all three conservation agriculture components would perform the best, resulting in more stable production in all environments. We evaluated at, eight trial locations across southern Africa, how partial and full implementation of these components affected crop yield and yield stability compared with conventional tillage alone or combined with mulching and/or crop rotation. Grain yield and shoot biomass of maize and cowpea were recorded along with precipitation for 2 to 5 years. Across different environments, the addition of crop rotation and mulch to no-tillage increased maize grain by 6%, and the same practices added to conventional tillage led to 13% yield increase. Conversely, adding only mulch or crop rotation to no-tillage or conventional tillage led to lower or equal maize yield. Stability analyses based on Shukla’s index showed for the first time that the most stable systems are those in which mulch is added without crop rotation. Moreover, the highest yielding systems were the least stable. Finally, additive main effects and multiplicative interaction analysis allowed clarifying that mulch added to no-tillage gives stable yields on sandy soil with high rainfall. Similarly, mulch added to conventional tillage gives stable yield on sandy soil, but under low rainfall. This is the first study that highlighted the crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa, supporting their adaptability to climate change.

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Effects of Management and Hillside Position on Soil Organic Carbon Stratification in Mediterranean Centenary Olive Grove

Agronomy ◽

10.3390/agronomy11040650 ◽

2021 ◽

Vol 11 (4) ◽

pp. 650

Author(s):

Jesús Aguilera-Huertas ◽

Beatriz Lozano-García ◽

Manuel González-Rosado ◽

Luis Parras-Alcántara

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Quality ◽

Management Practices ◽

Soil Management ◽

Olive Grove ◽

No Tillage ◽

Short Term ◽

Degradation Degree

The short- and medium—long-term effects of management and hillside position on soil organic carbon (SOC) changes were studied in a centenary Mediterranean rainfed olive grove. One way to measure these changes is to analyze the soil quality, as it assesses soil degradation degree and attempts to identify management practices for sustainable soil use. In this context, the SOC stratification index (SR-COS) is one of the best indicators of soil quality to assess the degradation degree from SOC content without analyzing other soil properties. The SR-SOC was calculated in soil profiles (horizon-by-horizon) to identify the best soil management practices for sustainable use. The following time periods and soil management combinations were tested: (i) in the medium‒long-term (17 years) from conventional tillage (CT) to no-tillage (NT), (ii) in the short-term (2 years) from CT to no-tillage with cover crops (NT-CC), and (iii) the effect in the short-term (from CT to NT-CC) of different topographic positions along a hillside. The results indicate that the SR-SOC increased with depth for all management practices. The SR-SOC ranged from 1.21 to 1.73 in CT0, from 1.48 to 3.01 in CT1, from 1.15 to 2.48 in CT2, from 1.22 to 2.39 in NT-CC and from 0.98 to 4.16 in NT; therefore, the soil quality from the SR-SOC index was not directly linked to the increase or loss of SOC along the soil profile. This demonstrates the time-variability of SR-SOC and that NT improves soil quality in the long-term.

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Carbon stocks in Tasmanian soils

Soil Research ◽

10.1071/sr11211 ◽

2012 ◽

Vol 50 (2) ◽

pp. 83 ◽

Cited By ~ 14

Author(s):

W. E. Cotching

Keyword(s):

Management Practices ◽

Agricultural Soils ◽

C Sequestration ◽

Mean Annual Temperature ◽

Soil C ◽

C Stocks ◽

Initial Soil ◽

If Current ◽

Intensive Cropping ◽

The Difference

Soil carbon (C) stocks were calculated for Tasmanian soil orders to 0.3 and 1.0 m depth from existing datasets. Tasmanian soils have C stocks of 49–117 Mg C/ha in the upper 0.3 m, with Ferrosols having the largest soil C stocks. Mean soil C stocks in agricultural soils were significantly lower under intensive cropping than under irrigated pasture. The range in soil C within soil orders indicates that it is critical to determine initial soil C stocks at individual sites and farms for C accounting and trading purposes, because the initial soil C content will determine if current or changed management practices are likely to result in soil C sequestration or emission. The distribution of C within the profile was significantly different between agricultural and forested land, with agricultural soils having two-thirds of their soil C in the upper 0.3 m, compared with half for forested soils. The difference in this proportion between agricultural and forested land was largest in Dermosols (0.72 v. 0.47). The total amount of soil C in a soil to 1.0 m depth may not change with a change in land use, but the distribution can and any change in soil C deeper in the profile might affect how soil C can be managed for sequestration. Tasmanian soil C stocks are significantly greater than those in mainland states of Australia, reflecting the lower mean annual temperature and higher precipitation in Tasmania, which result in less oxidation of soil organic matter.

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